1. Field of the Invention
The present invention relates to rotary type electronic parts such as, for example, rotary type variable resistors and rotary switches.
2. Description of the Prior Art
As an example of the rotary type electronic parts, there is for example a rotary type variable resistor hereinafter to be referred to as a volume as shown in FIG. 7. Referring to the drawing, the rotary device primarily consists of a case 4 formed of a front plate 1, a back plate 2, and a side plate 3 sandwiched therebetween, a rotary shaft 5 passing through parts from the front plate 1 to the back plate 2, sliders 6 as devices on the rotary side to be rotated by the rotary shaft 5, and substrates 8 provided with conductive patterns 7 as devices on the stationary side, with which the sliders 6 slidably contact.
Of the mentioned case 4, the front plate 1 is provided, on the operating side 5a of the rotary shaft 5, with a screwed portion 1e for fitting the same to a housing or the like, and on the side of the back plate 2 of the same, there is provided a recessed portion in which a slide member 9 with an annular spring 9a for providing necessary rotating torque mounted thereon can be inserted, the spring 9a being in slidable contact with the slide member 9. And, the slide member is mounted in the recessed portion 1d with the rotary shaft 5 passing therethrough. Further, a slider retainer 10 provided with the sliders 6 on both sides thereof together with the substrates 8, which are provided thereon with the conductive patterns 7 on the sides facing the sliders 6, are passed through by the mentioned slide member 9 and the rotary shaft 5, and integrated with the front plate 1, by the back plate 2 disposed in the rear of the substrate 8 on the left side in the drawing, by means of pins which are not shown. And further, an E ring 11 is fitted into a groove 5b provided in the end portion of the rotary shaft 5 on the side of the back plate 2, whereby the slider retainer 10 is integrally fixed to the rotary shaft 5. Denoted by 12 are terminals connected with the conductive patterns 7.
In the assembling of the above mentioned rotary device, the front plate 1 and the slide member 9 are put on the rotary shaft 5 from the rear end of the rotary shaft 5 in the order mentioned, then the spring 9a and the substrate 8 on the right side in the drawing are put on the shaft portion of the slide member 9, and then the slider retainer 10 is put on the rotary shaft 5. Thereafter, the E ring 11 is pressed from the side face into the groove 5b formed in the rotary shaft 5, whereby the rotary shaft 5 is made not to slip out of the slider retainer 10. In this case, the dimension between the fitted position of the E ring 11 and the stepped portion 5c of the rotary shaft 5 is precisely finished so that the component parts from the front plate 1 to the slider retainer 10 may be supported therein without a play, and thereby the rotating torque and the sliding pressure of the sliders 6 are regulated to be proper values and operability and precision in the operation are secured.
After, the side plate 3 regulating the distance between both the substrates 8 is inserted therebetween, the substrate 8 on the left side is put on the slider retainer 10 with a clearance, and pins, not shown, are inserted between the front plate 1 and back plate 2 and fixed by caulking with the back plate 2 pressed against the substrate 8 from the rear side.
In the prior art devices of the above described construction, there was a problem that efficiency in the assembling was bad because the E ring 11 had to be fitted into the groove 5b in the rotary shaft 5 with itself tightly abutted on the slider retainer 10 to secure operability and accurate operation, and also, because the small component parts had to be put on the rotary shaft 5 one after the other. And, since all the component parts had to be put in between the stepped portion 5c of the rotary shaft 5 and the E ring 11 with precision, each part had to be finished with high accuracy and this led to increase in the costs of the parts.